Class 12 Biology MCQ Chapter 13 Organisms and Populations
Are you looking for Class 12 Biology MCQ Chapter 13 Organisms and Populations English Medium? If yes, then you are in the right place. This article provides important MCQ questions with answers from Chapter 13: Organisms and Populations for AHSEC Higher Secondary students.
This chapter explains how organisms interact with their environment and how populations survive and adapt under different environmental conditions. Students will learn about habitat, ecological adaptations, population growth, population density, life history variations, and interactions between species such as competition, predation, parasitism, commensalism, and mutualism. These concepts are important for understanding ecology and environmental biology.
The MCQs are prepared according to the latest AHSEC syllabus and examination pattern. Practicing these objective questions will help students strengthen their concepts, improve their revision, and prepare effectively for board examinations.
Whether you are studying for class tests, model exams, or the AHSEC Higher Secondary Final Examination, these MCQ solutions will help you understand the chapter better and achieve higher marks in Biology.
Unit X: Ecology
Organisms and Populations
VSA & MCQ
I. Very Short Question-Answers
Q. What is ecology?
Ans: Ecology is the study of interactions between organisms and their environment.
Q. Define population.
Ans: Population is a group of individuals of the same species living in a particular area.
Q. What is habitat?
Ans: Habitat is the natural place where an organism lives.
Q. Define niche.
Ans: Niche is the functional role of an organism in an ecosystem.
Q. What are abiotic factors?
Ans: Abiotic factors are the non-living components of the environment.
Q. Name the most important abiotic factor affecting organisms.
Ans: Temperature is the most important abiotic factor affecting organisms.
Q. What is adaptation?
Ans: Adaptation is the adjustment of organisms to their environment for survival.
Q. Define acclimatisation.
Ans: Acclimatisation is the physiological adjustment of an organism to environmental changes.
Q. What is homeostasis?
Ans: Homeostasis is the maintenance of a constant internal environment.
Q. Define migration.
Ans: Migration is the seasonal movement of organisms from one place to another.
Q. What is hibernation?
Ans: Hibernation is a state of reduced metabolic activity during winter.
Q. What is aestivation?
Ans: Aestivation is summer sleep shown by some animals to avoid heat and dryness.
Q. Define population density.
Ans: Population density is the number of individuals per unit area.
Q. What is natality?
Ans: Natality is the birth rate in a population.
Q. Define mortality.
Ans: Mortality is the death rate in a population.
Q. What is immigration?
Ans: Immigration is the entry of individuals into a population from outside.
Q. What is emigration?
Ans: Emigration is the movement of individuals out of a population.
Q. Define carrying capacity.
Ans: Carrying capacity is the maximum population size that an environment can support.
Q. What is exponential growth?
Ans: Exponential growth is population growth under unlimited resources.
Q. Write the equation of exponential growth.
Ans: dN/dt = rN
Q. What is logistic growth?
Ans: Logistic growth is population growth under limited resources.
Q. Write the equation of logistic growth.
Ans: dN/dt = rN [(K − N)/K]
Q. What does ‘r’ represent in population growth equation?
Ans: ‘r’ represents intrinsic rate of natural increase.
Q. What does ‘K’ represent in logistic growth equation?
Ans: ‘K’ represents carrying capacity.
Q. Define mutualism.
Ans: Mutualism is an interaction in which both species are benefited.
Q. What is commensalism?
Ans: Commensalism is an interaction where one species benefits and the other is neither harmed nor benefited.
Q. Define parasitism.
Ans: Parasitism is an interaction in which one organism benefits while the other is harmed.
Q. What is predation?
Ans: Predation is an interaction where one organism kills and eats another organism.
Q. Define competition.
Ans: Competition is an interaction in which organisms compete for the same resources.
Q. What is camouflage?
Ans: Camouflage is an adaptation that helps organisms blend with their surroundings.
II. Multiple Choice Questions (MCQs)
Q. Ecology is the study of:
(a) Cells
(b) Tissues
(c) Organisms and environment
(d) Heredity
Ans: (c) Organisms and environment
Q. The place where an organism lives is called:
(a) Niche
(b) Habitat
(c) Population
(d) Community
Ans: (b) Habitat
Q. Which of the following is an abiotic factor?
(a) Bacteria
(b) Fungi
(c) Temperature
(d) Plants
Ans: (c) Temperature
Q. Summer sleep in animals is called:
(a) Hibernation
(b) Migration
(c) Aestivation
(d) Adaptation
Ans: (c) Aestivation
Q. Winter sleep is known as:
(a) Migration
(b) Hibernation
(c) Aestivation
(d) Homeostasis
Ans: (b) Hibernation
Q. Population density refers to:
(a) Number of species
(b) Number of individuals per unit area
(c) Biomass only
(d) Birth rate only
Ans: (b) Number of individuals per unit area
Q. Natality means:
(a) Death rate
(b) Birth rate
(c) Migration
(d) Competition
Ans: (b) Birth rate
Q. Mortality means:
(a) Birth rate
(b) Growth rate
(c) Death rate
(d) Survival rate
Ans: (c) Death rate
Q. The maximum population supported by environment is:
(a) Natality
(b) Mortality
(c) Carrying capacity
(d) Population density
Ans: (c) Carrying capacity
Q. Exponential growth occurs under:
(a) Limited resources
(b) Unlimited resources
(c) High mortality
(d) Competition only
Ans: (b) Unlimited resources
Q. Logistic growth occurs under:
(a) Unlimited resources
(b) No resources
(c) Limited resources
(d) High temperature only
Ans: (c) Limited resources
Q. In the equation dN/dt = rN, ‘r’ represents:
(a) Carrying capacity
(b) Population density
(c) Intrinsic rate of increase
(d) Mortality
Ans: (c) Intrinsic rate of increase
Q. The interaction in which both species benefit is:
(a) Parasitism
(b) Predation
(c) Mutualism
(d) Competition
Ans: (c) Mutualism
Q. Lichens are an example of:
(a) Predation
(b) Mutualism
(c) Competition
(d) Amensalism
Ans: (b) Mutualism
Q. The relationship between orchid and mango tree is:
(a) Parasitism
(b) Mutualism
(c) Commensalism
(d) Predation
Ans: (c) Commensalism
Q. Cuscuta is an example of:
(a) Commensalism
(b) Mutualism
(c) Parasitism
(d) Predation
Ans: (c) Parasitism
Q. Predation helps in:
(a) Species extinction only
(b) Maintaining ecological balance
(c) Increasing pollution
(d) Reducing biodiversity
Ans: (b) Maintaining ecological balance
Q. Competition occurs when organisms use:
(a) Different resources
(b) Same resources
(c) No resources
(d) Water only
Ans: (b) Same resources
Q. Adaptation helps organisms in:
(a) Extinction
(b) Survival
(c) Digestion only
(d) Respiration only
Ans: (b) Survival
Q. Camouflage is useful for:
(a) Reproduction only
(b) Hiding from predators
(c) Digestion
(d) Photosynthesis
Ans: (b) Hiding from predators
Q. Immigration causes:
(a) Decrease in population
(b) Increase in population
(c) Extinction
(d) Mortality
Ans: (b) Increase in population
Q. Emigration causes:
(a) Increase in population
(b) No change
(c) Decrease in population
(d) Mutation
Ans: (c) Decrease in population
Q. The graph of logistic growth is:
(a) J-shaped
(b) Straight line
(c) S-shaped
(d) Circular
Ans: (c) S-shaped
Q. The graph of exponential growth is:
(a) S-shaped
(b) J-shaped
(c) Zig-zag
(d) Circular
Ans: (b) J-shaped
Q. Which of the following is a parasite?
(a) Tiger
(b) Cuscuta
(c) Orchid
(d) Lichen
Ans: (b) Cuscuta
Q. Which interaction harms both species?
(a) Mutualism
(b) Competition
(c) Commensalism
(d) Predation
Ans: (b) Competition
Q. Homeostasis means:
(a) Migration
(b) Constant internal environment
(c) Reproduction
(d) Mutation
Ans: (b) Constant internal environment
Q. Population growth is affected by:
(a) Natality
(b) Mortality
(c) Migration
(d) All of these
Ans: (d) All of these
Q. The scientific study of populations is called:
(a) Genetics
(b) Demography
(c) Physiology
(d) Taxonomy
Ans: (b) Demography
Q. Which adaptation is shown by desert plants?
(a) Broad leaves
(b) Thick cuticle
(c) Thin stem
(d) Large stomata
Ans: (b) Thick cuticle
Q. Assertion (A): Population density changes with time.
Reason (R): Natality and mortality affect population size.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (b) Both A and R are true, but R is not the correct explanation of A
Q. Assertion (A): Logistic growth produces an S-shaped curve.
Reason (R): Resources become limited as population increases.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (d) A is false, but R is true
Q. Assertion (A): Mutualism benefits both interacting species.
Reason (R): Lichens show association between algae and fungi.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (c) A is true, but R is false
Q. Assertion (A): Predation maintains ecological balance.
Reason (R): Predators regulate prey population.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (a) Both A and R are true and R is the correct explanation of A
Q. Assertion (A): Camouflage helps organisms avoid predators.
Reason (R): Organisms resemble their surroundings.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (b) Both A and R are true, but R is not the correct explanation of A
Q. Assertion (A): Hibernation occurs during summer.
Reason (R): Animals reduce metabolic activity during unfavourable conditions.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (d) A is false, but R is true
Q. Assertion (A): Competition occurs between species using similar resources.
Reason (R): Resources in nature are always unlimited.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (c) A is true, but R is false.
